Field of the Invention
The present invention relates to communication cables, and particularly to optical fiber distribution cables for servicing a number of different customer living units or premises in a multi-dwelling unit (MDU) building.
Discussion of the Known Art
Increasing amounts of optical fiber cabling are being installed annually to satisfy demand for fiber-to-the-home (FTTH) communication services by customers occupying living units or other premises in multi-dwelling unit (MDU) buildings. The services typically include, inter alia, television, telephony, and Internet access. Recent advances in optical fiber and cable technology have facilitated such installations, particularly the development of ultra bend insensitive fibers (BIFs) such as, e.g., EZ-Bend® fiber available from OFS Fitel, LLC.
Notwithstanding, customers are increasingly sensitive to the visual impact of fiber cabling installations with respect to the immediate surroundings. In fact, potential customers will refuse installations only because the provider's cabling will have a negative visual impact. With the increasing availability of high bandwidth wireless services, cable service providers should ensure their installations will be virtually invisible to customers when completed.
Challenges remain with respect to routing multiple optical fibers through building hallways or passageways with minimal if any negative visual impact, and without adding costly moldings or trim to hide the fibers from open view. At present, one of two procedures is typically used.
In one procedure, a single distribution or “breakout” cable that contains multiple fibers within a common outer jacket or sheath, is adhered to a hallway wall over a path running next to or near each premises to be served by the fibers. Examples include MiniCord® and AccuPack® cables available from OFS Fitel, LLC. Once installed, the cables must be able to perform for more than 20 years, and comply with all applicable laws and codes pertaining to smoke and flammability. See, U.S. Pat. No. 7,720,338 (May 18, 2010), and Int. Pub. No. WO 2014/172285 (Oct. 23, 2014), both of which are incorporated by reference. In an installation procedure offered by 3M™ Company under the name “One Pass Pathways,” the fibers are contained inside a PVC duct or tube on which an outer adhesive strip is provided to adhere the duct along hallway wall.
In the other procedure, a bundle of individual buffered fibers or small optical fiber cables are tied to one another at reg ular intervals over the length of the bundle, and fastened to a hallway wall either with or without the addition of special moldings to hide the buffered fibers or cables from open view. The individual fibers are typically identified by either color-coding or application of a print string. In this procedure, the individual glass optical fibers, typically about 250 microns or larger in diameter, must be contained within a buffer coating or a small cable structure to protect the relatively fragile glass and to ensure compliance with all applicable laws and codes pertaining to smoke and flammability.
Neither procedure is optimal, however. Typical distribution cables may be relatively thick compared to the diameters of the fibers they contain. For example, the outer diameter (O.D.) of a typical 12-fiber distribution cable in which each fiber has a 900 micron tight buffer layer, is around 5 to 6 mm. The O.D. of a distribution cable containing twelve 250 micron colored fibers is still around 3 to 4 mm. Therefore, the installed cables can still be noticed by observers nearby.
In addition, a tied bundle of fibers each having an O.D. as small as 900 microns or 1.2 mm, can also be noticed when routed along a hallway wall. As mentioned, each fiber in the bundle often has a different color so an installer can identify the fiber and connect it to a drop fiber from a designated living unit. Thus, in this case, all the colored fibers in the bundle will remain visible and contribute to the negative visual impact of the installation, especially if the bundle is routed over or near a lightly colored wall, ceiling, or molding. Even if the fibers within the bundle are all of the same color, they can have a negative visual impact on installation due to the uneven surface of the bundle, resulting in some surfaces being shadowed.
A system known as EZ-Bend InvisiLight®, available from OFS Fitel, LLC, allows a single drop fiber to be installed inside a living unit by use of a tool that routes and adheres a flame-retardant, plastic-coated 900 micron fiber along existing moldings at the premises, inside corners between ceilings and walls, and inside corners between walls and moldings, leaving the entire installation virtually invisible. See, U.S. Pat. No. 8,792,766 (Jul. 29, 2014), No. 8,574,385 (Nov. 5, 2013), and No. 8,906,178 (Dec. 9, 2014), all of which are incorporated by reference in their entireties.
In view of the above, there is still a need for an optical fiber distribution or breakout cable that contains fibers of different colors for easy identification, but which has little if any negative visual impact after the cable is routed and installed through a building hallway or passageway to service customers in the building.